[PATCH] D33521: [sanitizer] Pair atomic acquire with release in BlockingMutex::Unlock

[Aleksey Shlyapnikov via Phabricator via llvm-commits]

alekseyshl created this revision.
Herald added a subscriber: kubamracek.

Dmitry, seeking your expertise. I believe, the proper way to implement
Lock/Unlock here would be to use acquire/release semantics. Am I missing
something?


https://reviews.llvm.org/D33521

Files:
  lib/sanitizer_common/sanitizer_linux.cc


Index: lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cc
+++ lib/sanitizer_common/sanitizer_linux.cc
@@ -549,7 +549,7 @@
 
 void BlockingMutex::Unlock() {
   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
-  u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
+  u32 v = atomic_exchange(m, MtxUnlocked, memory_order_release);
   CHECK_NE(v, MtxUnlocked);
   if (v == MtxSleeping) {
 #if SANITIZER_FREEBSD


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